In recent years there has been increasing use of coated glass in the construction industry, especially in spandrel and interior design applications, since such glass is substantially less expensive than conventional exterior materials such as brick and granite and presents aesthetically appealing design choices for interiors. Metallic coatings have been applied to enhance both the aesthetic appeal and reflectively of such glass, the latter also helping to conserve energy in buildings. Ceramic frit coatings have been used to color and to opacify glass. However, ceramic frit-coated glass has several serious drawbacks. One such drawback is the presence of substantial amounts of lead in the ceramic frit coating composition. Lead, a toxic metal, requires special care in handling during ceramic frit coating processes and, in fact, its use in ceramic frit coating is now prohibited by regulations of the United States Environmental Protection Agency.
Ceramic enamels have also been used for coating automobile glass to render it opaque for ultraviolet (UV) protection of reinforcing materials such as urethane adhesives and for application of shading designs on the glass. However, ceramic enamels require high-temperature curing with a lead-containing flux material. The heavy and toxic metal cadmium is also present in ceramic enamels as pigment and, consequently, the use of ceramic enamels raises environmental concerns.
There is therefore a need in the art for a glass coating that enhances the durability and insulative and decorative properties of architectural grade glass and automobile glass, that can render the same opaque and impart color thereto, and that can withstand the elements, all without adding any hazardous materials to the environment. These needs and others are met by the process and resulting product of the present invention, which is summarized and described in detail below.